This invention relates to d.c. electric motors for automotive applications and, more particularly, to a choke having features for improved mechanical and electrical connection with components of a brush card assembly.
Typical multi-pole automotive d.c. electric motors use bus bars to conduct current between the electrical connector of the motor and associated components such as chokes, capacitors, and brushes. Conventional bus bars have to be manufactured and physically attached, supported and connected with the motor. Typically, the bus bars are riveted to the brush card of the motor. The electrical connection is usually achieved using soldered or heat-fused joints.
Thus, there is a need to reduce the number of electrical connections required on the motor""s brush card, to eliminate costly bus bars and to reduce the number of separate mechanical fasteners needed on the brush card.
Furthermore, conventionally, wound wire coils or chokes are installed close to the brushes of d.c. motors, particularly in automotive applications. The purpose of the chokes is to suppress radio-frequency interference (RFI) generated by the motor. Generally, the chokes are physically attached to the brush card of the motor using fixing or fastening techniques that require additional specific parts or processes, for example, the ends of the chokes may be soldered to conductors that are riveted to the brush card, and/or clips or other fasteners may be used to attached the chokes.
Another way of attaching chokes 10 to the brush card 12 is shown in FIG. 1. Connecting portions 14 of each choke 10 are inserted through an associated opening 16 in the brush card 12 and then the connecting portions 14 are bent to secure the choke to the brush card. Although no additional fasteners are used to attach this type of choke, additional bending steps are required which increases labor costs.
Hence, there is also a need to provide secure mechanical attachment of the choke to the brush card while avoiding the necessity specific fastening components or additional assembly procedures.
An object of the present invention is to fulfill the needs referred to above. In accordance with the principles of the present invention, this objective is obtained by providing a choke for suppressing radio-frequency interference of a brush-type motor. The choke includes a single wire having a portion wound about a coil axis to define a plurality of coils including two outermost coils. An attaching structure extends from one of the outermost coils and includes a loop structure. The loop structure is constructed and arranged to be inserted into a slot in a brush card and moved into hooked relation with a retaining member of the brush card associated with the slot, so as secure the choke to the brush card. At least a portion of the attaching structure is constructed and arranged to be in electrical connection with a brush of the brush card when the choke is secured to the brush card. An elongated end portion extends directly from the other outermost coil. The elongated end portion is constructed and arranged to be directly electrically connected to an electrical connector of the brush card when the choke is secured to the brush card.
In accordance with another aspect of the invention, a brush card assembly for a d.c. motor includes at least one choke composed of a single wire having a portion wound about a coil axis to define a plurality of coils including two outermost coils. An attaching structure extends from one of the outermost coils and includes a loop structure. An elongated end portion extends from the other of the outermost coils. A brush card has a top side and an opposing bottom side and slot through the opposing sides. The brush card includes a retaining member adjacent to the slot. The loop structure is received in the slot and is in hooked relation with the retaining member such that the choke is secured to the brush card. A brush is mounted on the brush card and is in electrical connection with at least a portion of the attaching structure. An electrical connector is mounted on the brush card and receives at least a part of the elongated end portion of the choke.
In accordance with yet another aspect of the invention, a method of connecting a choke to a brush card assembly is provided. The choke includes a single wire having a portion wound about a coil axis to define a plurality of coils including two outermost coils. An attaching structure extends from one of the outermost coils and includes a loop structure. An end portion extends from the other outermost coil. The brush card assembly includes a brush mounted on the brush card, and an electrical connector mounted on the brush card. In the method, the loop structure is inserted into the slot of the brush card and is moved into hooked relation with the retaining member of the brush card, thereby securing the choke to the brush card. The elongated end portion is electrically connected to the connector. A portion of the attaching structure is electrically connected to the brush.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.